The modification of reactivity at silicon centre by a remote phosphorus group

Article abstract of DOI:10.1016/0022-328X(88)83146-2

The compounds X(CH2)nSiMe2(OPh) (X = H, n = 2, 3; X = PPh2, n = 1, 2, 3; X = P(O)Ph2, n = 2, 3; X = P(S)Ph2, n = 1, 2, 3) having silicon and phosphorus bridged by carbon chains, have been synthesized.The kinetics of acid- and basecatalysed solvolytic cleavage of phenoxyl group from these compounds in methanol have been investigated.The kinetic results obtained in the presence of bases can be interpreted in terms of polar and steric effects alone, but there was an unexpected enhancement of the reactivity in the case of the P=O-containing substrates in the acidic media.The solvent kinetic isotope effects are best interpreted in terms of participation by the P=O group as a base rather than as a nucleophile attacking the silicon centre.